A Device-to-Device (hereinafter referred to as ‘D2D’) (or Peer-to-Peer) communication network refers to a network that performs direct communication between adjacent devices without an infrastructure consisting of a centralized access point such as a base station, an Access Point (AP) or the like. In the D2D communication network, a wireless terminal identifies, on its own, geographically adjacent neighboring terminals, and if necessary, establishes a wireless link with a specific neighboring terminal and transmits data. Since this process basically has a distributed performance between terminals without the help of other devices, the D2D communication has an advantage in that rapid market introduction is possible without a separate infrastructure compared to other wireless communication networks. In addition, the D2D communication may also solve the problem of traffic overload which has currently been centered on the base station or AP by locally accommodating data traffic. For these reasons, standards organizations such as 3rd Generation Partnership Project (3GPP), Institute of Electrical and Electronics Engineers (IEEE) and the like have been promoting the establishment of D2D communication standards based on Long Term Evolution (LTE)-advanced or Wireless-Fidelity (Wi-Fi) and Qualcomm Inc., along with others have also been developing proprietary D2D communication technologies.
In the D2D communication network, terminals (or the devices) have to have a capability to form a D2D link with another terminal on their own without the assistance of a base station or AP and perform data communication through the D2D link. During the process, a distributed link scheduling method for determining when or through which wireless resources each of multiple D2D links transmits data is very important in relation to the performance of the D2D communication network. Qualcomm Inc. proposed a distributed link scheduling technique considering a Signal-to-Interference ratio (hereinafter referred to as ‘SIR’) between links through an Orthogonal Frequency Division Multiplexing (OFDM) signal architecture-based single-tone detection signal exchange by terminals in a synchronized wireless environment: X. Wu, S. Tabildar, S. Shakkottai, T. Richardson, J. Li, R. Laroia, and A. Jovicic. FlashLinQ: A synchronous Distributed Scheduler for Peer-to-Peer Ad Hoc Networks, Technical Report, 2010.
FlashLinQ, a wireless communication technique capable of a single-hop communication from one terminal to another terminal within a 1 (one) km radius from each other, supports a high performance D2D communication for multiple D2D links by considering the estimated amount of interference instead of considering carrier sensing in determining on which link to transmit. However, when the respective D2D links randomly transmit power in FlashLinQ, the performance of the entire D2D network may be deteriorated because a degree (level) of the transmission power control has a direct effect on the SIR-based distributed link scheduling result. Thus, a method for controlling the transmission power of each D2D link needs to be devised so as to improve the performance of the entire network in the D2D communication network using distributed link scheduling.